An experiment has been conducted with the purpose of examining the effect of two kinds of probiotic on the behavior and blood H/L ratio of local ducks kept in commercial farms. The study was conducted in collaboration with the ‘Berkah Abadi’ duck farmer group which keeps the bird under an intensive dry system. The intensive system refers to the ordinary way done by the farmers in which ducks were confined around the farmer’s village with a closed fence so the birds had no access to the outside area, and the amount of feed provided could be controlled and measured. The location was in the coastal area of Tegal City as one of the most famous duck centers in Indonesia. The materials used were 13.4+1.3 months old local laying ducks which were reared by the farmer group. The study used a Completely Randomized Design with treatments consisting of 3 doses of P and P+ probiotics respectively. P contained Lactobacillus sp. combined with Saccharomyces cerevisiae, whereas P+ comprised Lactobacillus sp., Saccharomyces cerevisiae, Streptococcus thermophilus, and Lactobacillus bulgaricus. There were 6 treatment units which were replicated 4 times, so in total there were 24 flocks. Each flock had 50 female ducks; therefore this study involved 1,200 ducks. The treatments were applied each morning, and mixed thoroughly in duck ration. Data collected were heat stress-related behavior, body temperature, and H/L ratio. It was concluded that P and P+ had similar effects on the behaviour and H/L ratio of local ducks kept under commercial management.